1. Field of the Invention
This application relates to a screening methodology for identifying individuals having a predisposition to develop or have ovarian cancer.
2. Prior Art
Ovarian cancer remains notoriously difficult to detect in its early stages. Over 80% of female ovarian carcinomas are thought to arise from the OSE. OSE-derived carcinomas are the fifth or sixth most frequent malignancy in American women and the five year survival rate of patients with ovarian cancer is less than 40%. A significant need therefore remains for a new screening test for identifying and monitoring women at risk of developing OSE-derived carcinomas.
There exist various tests for the presence of female specific cancers including, for example, mammography for breast cancer and pap smears for cervical cancer. Prior hereto, inadequate methodology exists for ovarian cancer screening.
One commonly used test for ovarian cancer involves measuring the phenotypic expression of the CA125 antigen in overtly normal ovarian surface epithelium cells propagated in vitro. Recently, the use of tumor markers, such as serous cystadeno carcinoma ovarian tumor associated antigen CA125 for monitoring the progression of ovarian surface epithelium (OSE) carcinomas, has improved diagnostic and prognostic accuracy in the management of ovarian carcinomas. Elevated serum levels of CA125 antigen are detectable in approximately 80-90% of ovarian cancer patients. The presence of CA125 is typically detected by radioimmunoassays employing monoclonal antibodies such as OC125 which bind specifically to the CA125 antigenic determinant.
Although the measurement of serum CA125 levels is an effective tool for monitoring the progression of ovarian cancers, it does not aid in providing a screening test as a predictive marker for identifying healthy women at increased risk for ovarian cancer, or for detection of very early stages of the disease.
Genetic analysis is another helpful methodology to determine women who are at an increased risk of developing ovarian cancer. This alone, however, is insufficient and additional contributing factors are poorly defined. Of equal importance, a significant number of ovarian cancers arise in women without family histories.
One potential alternative strategy is to identify preneoplastic phenotypic changes in the OSE which could signal a predisposition to development of ovarian tumors. To date, however, little progress has been made in the early detection of such preneoplastic tissue changes and no reliable tumor-associated tissue markers have yet been identified. This lack of information about early changes in the OSE poses a particular problem for women with hereditary ovarian cancer syndromes, in which there is an urgent need to define more reliable criteria for prevention and surveillance. One test uses a scrape method with a laparoscope to gain cell cultures. The cultured cells use the OSE cells in vitro to obtain a population of propagated OSE cells derived from the sample. The expression of CA125 antigen by said propagated OSE cells was measured to indicate the predisposition of ovarian cancer. This screening method misses nearly one-half of early stage cancers.
Still another test employed uses transvaginal sonograms (ultrasound). This has been effective for determining presence of existing abnormalities with the tissue, but trans-vaginal ultrasound cannot distinguish between early stage cancers and other abnormalities such as benign cysts.
In contrast, pap smear tests for automated screening of cytological smears for dense, possibly malignant cells have proven to be useful in detecting other cancers, such as cervical. However, the pap smear test is presently not used in the area of ovarian cancer detection for the lack of a suitable tissue extraction method. A pap smear test typically includes a specimen slide for receiving a cytological smear and a microscope for viewing the image of the smear.
The present invention provides a solution to the deficiencies in the art.